Re: [PATCH net v1 2/2] net: stmmac: eic7700: fix delay step calculation and ensure safe register initialization

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Critical] Unconditional ABI breakage with older Device Trees
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commit 8a3e405f7bc380e02d2d33cd362d35a040182e99
Author: Zhi Li <lizhi2@eswincomputing.com>

net: stmmac: eic7700: fix delay step calculation and ensure safe register initialization

This commit updates the EIC7700 DWMAC glue driver to match hardware delay
granularity and moves HSP CSR configuration to the initialization path. It
also introduces new offsets and clears the TXD/RXD delay control registers
during setup to ensure deterministic RGMII timing.

> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-eic7700.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-eic7700.c
> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-eic7700.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-eic7700.c
[ ... ]
> +	ret = of_property_read_u32_index(pdev->dev.of_node,
> +					 "eswin,hsp-sp-csr",
> +					 3, &dwc_priv->eth_clk_offset);
> +	if (ret)
> +		return dev_err_probe(&pdev->dev, ret,
> +				     "can't get eth_clk_offset\n");
>  
> +	ret = of_property_read_u32_index(pdev->dev.of_node,
> +					 "eswin,hsp-sp-csr",
> +					 4, &dwc_priv->eth_txd_offset);
> +	if (ret)
> +		return dev_err_probe(&pdev->dev, ret,
> +				     "can't get eth_txd_offset\n");

Will this break compatibility with older device trees that only provide 3
indices for the eswin,hsp-sp-csr property?

If the driver boots with an older device tree, of_property_read_u32_index
will return an error when attempting to read index 4, causing the probe to
fail entirely and resulting in a loss of network functionality.

Could the new offsets at index 4 and 5 be made optional, or handled with a
backward-compatible fallback, to preserve the device tree ABI?

> +	ret = of_property_read_u32_index(pdev->dev.of_node,
> +					 "eswin,hsp-sp-csr",
> +					 5, &dwc_priv->eth_rxd_offset);
> +	if (ret)
> +		return dev_err_probe(&pdev->dev, ret,
> +				     "can't get eth_rxd_offset\n");

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Sashiko AI review · https://sashiko.dev/#/patchset/20260507083037.152-1-lizhi2@eswincomputing.com?part=2